Definition of Knee jerk

Reviewed on 3/29/2021

Knee jerk: The reflex that is tested by tapping just below the bent knee on the patellar tendon. Normally this causes the quadriceps muscle to contract and bring the lower leg forward. It has given rise to the saying 'a knee-jerk reaction.' Also known as patellar reflex.


Brain Food Pictures: What to Eat to Boost Focus See Slideshow

Health Solutions From Our Sponsors